Supply of electricity from power generators such as power stations, to consumers, such as domestic households and businesses, typically takes place via an electricity distribution network. FIG. 1 shows an exemplary distribution network comprising a transmission grid 100 and a distribution grid 102. The transmission grid is connected to generating plants 104, which may be nuclear plants or gas-fired plants, for example, from which it transmits large quantities of electrical energy at very high voltages (in the UK, for example, this is typically of the order of 204 kV; however this varies by country), using power lines such as overhead power lines, to the distribution grid 102; although, for conciseness, only one distribution grid 102 is shown here, in practice a typical transmission grid supplies power to multiple distribution grids. The transmission grid 100 is linked to the distribution grid 102 via a transformer node 106, which includes a transformer 106 which converts the electric supply to a lower voltage (in the UK, for example, this is typically of the order of 50 kV; however, this varies by country) for distribution in the distribution grid 102. The distribution grid in turn links, via substations 108 comprising further transformers for converting to still lower voltages, to local networks such as a city network 112 supplying domestic users 114, and to industrial consumers such as a factory 110. Smaller power generators such as wind farms 116 may also be connected to the distribution grid 102, and provide power thereto.
The total power consumption associated with a given network varies considerably from time to time; for example, peak consumption periods may occur during the hottest part of the day during summer, when many consumers use their air conditioning units. Since it is expensive to store electricity in large quantities, it is usually generated when it is required, which can place a burden on power generators as they attempt to meet demand at peak times. Furthermore, in recent years, a greater proportion of electricity is being generated by intermittent renewable energy forms, such as solar or wind power, whose ability to generate power is dependent on environmental conditions that are difficult to predict and are beyond the control of the operator of the power generator. There may also be considerable variation in demand for electrical energy between different geographical areas; it may be difficult to supply the required amount of electric energy to areas of high demand, known as “hot spots”, resulting in potential power cuts in these areas, and/or an inefficient distribution of network resources.
Accordingly, there is an increased demand for more efficient ways of managing energy consumption in electricity networks. Approaches to this problem having included providing users with pricing and other information, with the user being required to monitor an energy tariff on e.g. a smart meter, and respond to price signals from an electricity supplier. However, this places considerable burden on the user performing the monitoring. Other approaches have included methods of remotely monitoring electricity consumption devices in the network at a central location, and sending commands to disable the devices during times of high demand. However, this approach can cause considerable inconvenience to users, who may be unable to use their devices for extended periods of time.
It is an object of the present invention to at least mitigate some of the problems of the prior art.